How to Measure Your PD

Your PD — pupillary distance — is the gap between the centres of your pupils, in millimetres. It tells us where to place the optical centre of each lens. Get it right and your glasses feel effortless; get it wrong and strong prescriptions can feel like they pull at your eyes.

Check your prescription first

Many prescriptions already list it, written as PD or DPD. It may be a single number (e.g. 63) or two (e.g. 31.5 / 31.5), one for each eye. If it is there, use it and skip the rest of this page.

Measure it yourself with a ruler

1. Stand about 20 cm from a mirror, holding a millimetre ruler flat against your brow.
2. Close your right eye. Line the ruler's 0 up with the centre of your left pupil.
3. Without moving the ruler, open your right eye and close your left.
4. Read the number that now sits over the centre of your right pupil. That is your PD.
5. Do it three times and take the middle number.

What is normal

Most adults measure between 54 mm and 74 mm. Most children measure between 43 mm and 58 mm. If your number lands far outside that, measure again — it is usually a slipped ruler.

If you are ordering progressives

Progressive lenses are less forgiving about PD than single vision. If you are not confident in your measurement, ask your optician for it — they will normally give it to you for free — or choose Send It Later at checkout and we will follow up.

Still unsure? Email info@eyewinsome.us and we will walk you through it.